LONDON — The British Museum has pledged not to dismantle its collection, following a report that the institution’s chairman has held secret talks with Greece’s prime minister over the return of the Parthenon Sculptures, also known as the Elgin Marbles.

The report by the Greek newspaper Ta Nea is the latest twist in the long-running dispute over ownership of the ancient sculptures, which originally stood on the Acropolis in Athens and have been a centerpiece of the British Museum’s collection since 1816.

Ta Nea reported Saturday that negotiations between museum Chairman George Osborne and Greek Prime Minister Kyriakos Mitsotakis have been taking place since November 2021 and are at an advanced stage.

While the museum didn’t deny that talks have taken place, a spokesman refused to discuss the specifics of the Ta Nea story. The museum said it was prepared to “talk to anyone, including the Greek government’’ about a new Parthenon “partnership.’’

“As the chair of trustees said last month, we operate within the law and we’re not going to dismantle our great collection as it tells a unique story of our common humanity,’’ the museum said in a statement released Saturday. “But we are seeking new positive, long-term partnerships with countries and communities around the world, and that of course includes Greece.”

The Greek government offered no comment on the report.

Although British authorities have rebuffed efforts to return the sculptures to Greece since at least 1941, there has been a change of tone recently as museums around the world seek to address concerns about the way ancient artifacts were acquired during periods of imperial domination and colonial expansion.

In July, Jonathan Williams, the British Museum’s deputy director, said the institution wanted to “change the temperature of the debate” around the marbles.

“What we are calling for is an active ‘Parthenon partnership’ with our friends and colleagues in Greece,’’ he told the Sunday Times. “I firmly believe there is space for a really dynamic and positive conversation within which new ways of working together can be found.”

On its website, the museum says it is willing to consider loaning the sculptures to Greece, but that successive Greek government’s have refused to acknowledge the museum’s ownership. There are no current negotiations about the issue, the museum says.

Speaking during a visit to London on Nov. 28, Greek PM Mitsotakis implied that some talks have taken place.

“I don’t want to speak publicly about the discussions that we have had,” he said. “But I think there is a better sense of understanding that maybe a win-win solution can be found that will result in a reunification of the Parthenon Sculptures in Greece, while at the same time also taking into consideration concerns that the British Museum may have.”

The issue is complicated by an act of Parliament that prohibits the museum from selling, giving away or otherwise disposing of any items in its collection unless they are duplicates or not needed for study.

The marbles are remnants of a 160-meter-long (520-foot) frieze that ran around the outer walls of the Parthenon Temple on the Acropolis, dedicated to Athena, goddess of wisdom. Much was lost in a 17th-century bombardment, and about half the remaining works were removed in the early 19th century by a British diplomat, Lord Elgin.

They ended up in the British Museum, which has repeatedly rebuffed Greek demands for their return.

Successive Greek governments have lobbied for the return of the British Museum’s share of the works, which include statues from the Parthenon’s pediments — the all-marble building’s gables. They argue that Elgin illegally sawed off the sculptures, exceeding the terms of a questionable permit granted by Turkish authorities while Greece was an unwilling part of the Ottoman Empire.

The British Museum rejects that stance — despite indications that public opinion in the U.K. favors the Greek demand — and has shown little willingness to permanently return the works.

The Parthenon was built between 447-432 B.C. and is considered the crowning work of classical architecture. The frieze depicted a procession in honor of Athena. Some small bits of it — and other Parthenon sculptures — are in other European museums.